Family feud over Johnny Hallyday's estate

French rock star Johnny Hallyday's daughter Laura Smet and son David are disputing his will.

A feud has erupted over the estate of French rocker Johnny Hallyday, who died two months ago, with two of his four children aggrieved that they have seemingly been cut out of a will that may be worth as much as 100 million euros ($A156 million).

Lawyers for Hallyday's actress daughter Laura Smet, 34, said she was taking legal action to contest a will that appears to leave everything to his fourth wife Laeticia, 42, who mostly lives in Los Angeles.

Separately, a lawyer for David Hallyday, who was born to Johnny Hallyday's first wife Sylvie Vartan in 1966, said he was planning to join his half-sister in challenging the will, which was drawn up under Californian law.

The hard-living rocker, known as the French Elvis, died in December at the age of 74 after a battle with lung cancer. During his nearly 60-year career, he sold more than 100 million records, building up a valuable but dispersed estate. He is buried on the Caribbean island of Saint Barthelemy.

In a statement issued by her lawyers, Smet said she was "stunned and pained" to discover she had been excluded from the inheritance.

"If this were to be, her father will have left her nothing: no material goods, no stake in his artistic legacy, no souvenir, no guitar, no motorbike - not even a signed cover from the song he dedicated to her," the statement said.

The document, Smet's lawyers said, seemingly runs counter to French law, which specifically protects children from being disenfranchised in a will.

While the details of the document and the size of his estate have not been made public, the lawyers said it appeared to leave everything to Laeticia, who Hallyday married in 1996, when she was 21.

French media estimates of his wealth vary wildly, with some saying it may be as much as 100 million euros but others saying it could be far lower because of debts.

Hallyday, famed for a rock star lifestyle that involved a lot of hard drugs and whisky, spent much of his later years in Los Angeles, indulging his love of motorbikes and sports cars.

He was married five times, including twice to the same woman, Adeline Blondiau.

To add to the complications of his estate, Hallyday was never married to Smet's mother, actress Nathalie Baye.

Hallyday married Laeticia Boudou in 1996. They adopted two girls born in Vietnam, the first in 2004 and the second in 2008, who in theory will be in line to inherit via their mother.